This invention relates to compositions, methods and kits for detecting the presence and/or amounts of certain narcotic analgesics in samples suspected of containing the same. In particular, the present invention relates to homogeneous immunoassays and compositions of matter that are useful in conducting immunoassays for oxycodone and its metabolites such as, for example, oxymorphone. Homogeneous immunoassays have the advantage of not requiring separation steps. Such assays, however, are limited by the difficulty of providing antibodies that will modulate the activity of a label that is normally bound to the antibodies or an analog of the analyte. The present invention overcomes these difficulties and provides immunogenic conjugates for preparation of antibodies and label conjugates such as, for example, glucose-6-phosphate dehydrogenase (G6PDH) conjugates, useful in immunoassays for oxycodone and its metabolites.
The clinical diagnostic field has seen a broad expansion over the years, both as to the variety of materials of interest that may be readily and accurately determined, as well as the methods for the determination. Over the last few decades, testing for therapeutic drugs and drugs of abuse has become commonplace. This testing is not only for the monitoring of criminal offenders and drug addicts, but employers also use it for the screening of workers. Immunoassays based on the reaction of an antibody with an antigen have been extensively investigated for this purpose. Some categories of immunoassays include a radioimmunoassay, using a radioactive isotope, an enzyme-based immunoassay (EIA) using an enzyme, and luminescence assays, using fluorescent labels, e.g., fluorescence polarization, and chemiluminescent labels.
The clinically important and potent analgesic oxycodone is a narcotic analgesic generally indicated for relief of moderate to severe pain. Oxycodone is available as a single ingredient medication in immediate release and controlled release forms. Oxycodone is also formulated with non-narcotic ingredients such as non-steroidal anti-inflammatory drugs (NSAIDs) and acetaminophen and/or with other materials to reduce side effects of oxycodone.
There is, therefore, a need for assays for the detection of oxycodone and its major metabolites such as, for example, oxymorphone. The assays should be able to detect these drugs in order to monitor and treat patients. Antibodies bind to label conjugates in accordance with the principles described thereby providing requisite modulation of signal from the label of the conjugates by the binding of antibodies to the conjugate.